Sound-reproducing apparatus



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S 6 2 9 1 2 v o N Filed July 27, 1925 atented or. 2, 192. v

LEO L. HUGHES, OF WASHINGTON, DISTRICT OF COLUMBIA.

SOUND-REPRODUCING APPARATUS.

Application filed ll'uly 27, 1925. Serial No. 46,443.

lhis invention relates to sound reproducing apparatus and particularly to mechanism for the amplification of sounds in the instrument now commonly known as the loud speaker used in connection' with radio receiving apparatus.

In devices of this character there is usually a diaphragm with which there is operatively associated the armature of a coil magnet, said armature being pivotally mounted so that its rocking movement can effect impulses, so to speak, on the diaphragm. With arrangements such as these it has always been desirable to provide means for varying the leverage of the armature so that the sounds emitted from the instrument could be properly varied. In effecting this tuning operation it has also been found that much better results could be obtained if the air gap between the armature and the pole piece of the coil magnet could be varied in accordance with the variations in the leverage of the armature.

The primary object of the present inven-. tion, therefore, is to provide a sound amplifying apparatus wherein the leverage of the armature and the air gap between said armature and the pole piece of the coil magnet may be adjusted simultaneously and at will.

A further object is to incorporate in the present construction an arrangement which will permit the air gap to be enlarged up to a certain extent, after which said air gap will remain constant while permitting a continued adjustment of the leverage of the armature.

With these and other objects in view, the

invention consists in certain novel details of construction and arrangements and combijnations of-parts all as will be hereinafter more fully described and the novel features I thereof-particularly pointed out in the aptaken centrally of the pole piece of the coil pended claims.

' in the accompanying drawings Figure 1 is a horizontal sectional view of a sound amplifying apparatus embodying the present improvements, some of the parts being shown more or less conventionally; and

Fig. 2 is a longitudinal sectional View magnet and the cooperating portion of the armature.

. Fig. 3 is a perspective View of the pole piece; and

Fig. 4: is a transverse sectional view of the pole piece and cooperating portion of the armature.

In the structure shown for illustrating one application ofthe present invention, there is a hornor other sound director 10 mounted in the supporting frame 11 and at the inner end of said sound director 10 there is the diaphragm 12 which may be of any desired type.

Operatively associated with diaphragm 12 is the armature 13- pivoted at 14 to a bracket carried by frame 10, a portion of said armature being adapted to actuate, either directly or indirectly, the diaphragm and another portion thereof, as at 15, being adapted to cooperate with the pole piece 16 of a coil magnet 17 which is preferably fixedly secured to one arm of a permanent magnet 18.

ltn order that the pole piece of the coil magnet 17 maybe adjusted toward and from the pivot M of the armature to vary the leverage of the latter, the permanent magnet is slidably secured in the frame 10, a movement of said magnets toward and from said pivpivotal point being obtained by manipulation of a screw 19 journaled in'frame 10 and extendng through a threadedopenng in the permanent magnet. To secure minute adjustment of the magnets with respect to the armature, the screw'19 carries a gear 20 which imeshes with a smaller gear 21 that may be rotated by a thumb nut 22 at the exterior of the frame. Asbefore pointed out, it is desirable to vary the air gap between pole piece 16 and the cooperating surface 15 of the armature in accordance with the variations in the leverage of said armature. For this purpose the pole piece 16 and cooperating face '15 have a portion of their opposed surfaces inclined with respect to the plane in which said pole piece may be moved by screw 19, said opposed surfaces being reversely inclined so that as'pole piece 16 is moved from pivot-14 the opposed surfaces will be brought nearer each other to cut down the air gap while a movement of the pole piece toward the pivotal center 14: will effect a separation of the opposed faces, thus increasing or enla-rging said air gap.

.With this arrangement it will be seen that turning screw 19 in one direction will effect a decrease in leverage of armature 13 and will simultaneously effect a corresponding decrease in the air gap while, on the other hand, turning said screw in the opposite direction will result in simultaneously increasing the leverage of the armature and enlarging the air gap. A. convenient arrangement for allowing a sliding movement of the permanentmagnet 18 consists in providing the non-conducting carrier 27, in which the screw 19 is journaled, with an arm 28 formed with a groove or slideway for one arm of said magnet, the other arm being slidably supported in another track 29 formed of strips of suitable material attached to the inner wall of the frame 11.

As will be apparent, movement of pole piece 16 toward thecenter 14 may, under some conditions, cause ,the air gap to be increased to a point where the magnet would cease to attract armature 13. To eliminate this possibility of the apparatus failing to function properly, the remaining opposed portions of the faces of pole piece 16 and the cooperating surface of the armature are so arranged with respect to each other that the distance between them cannot be varied by'a movement of the pole piece. Preferably, said remaining opposed portions are -v equi-distantly spaced apart throughout their length and lie in planes parallel to the plane of movement-of the pole piece 16. With this arrangement should the desired leverage for the armature require the pole piece to be moved so far toward the pivot 14: that the inclined portions of the cooperating surfaces till tilt) (ill will be separated to an extent that the armature will be out of or beyond the zone of operation so far as those inclined portions are concerned, nevertheless, the other portions of the cooperating surfaces which lie parallel to the plane of movement of the pole piece will remain operatively as sociated to effect actuation of the armature. In other words, those opposed portions of the armature and pole piece which are parallel to the plane of movement of the latter limit the movement of the armature and pole piece so far as the air gap is concerned while still permitting a further adjustment of the leverage of the armature.

As illustrated, the two side portions-- 23 of the pole piece are inclined with respect to the plane of movement of said pole piece while the opposed portions 24 of the armature are similarly inclined but in a reverse direction and the intermediate portions 25, 26 of the pole piece and armature, respectively, are arranged parallel to the plane of movement of the pole piece. In order to eliminate any side pull being exerted by pole piece 16 on the armature, the inner side faces of the inclined portions 23, 241-, and the proximate side tapes of the portions 25,

eeaesr 26, of the pole piece and armature may be made COIIVQK. This specific embodiment is the preferred arrangement but it will be Understood that the same may be varied while still securing the objects contemplated by the present invention. Likewise, it will be understood that the invention is not limited to use in connectionwith any particular form of sound transmitting apparatus and limitations in these respects are not to be placed on the following claims except where express limitations are included.

What it claim is:

1.. In a sound reproducing apparatus, a

diaphragm, a permanent magnet, a coil magnet operatively associated with the permanent magnet, an armature adapted to be actuated by the coil magnet, said armature being pivoted adjacent the diaphragm and operatively associated therewith, and means for simultaneously varying the .air space between the coil magnet and the armature and for, varying the leverage of the pivoted armature.

'2. In a. sound reproducing apparatus, a diaphragm, a permanent magnet, a coil magnet associated with the permanent magnet, an armature pivotally mounted in operative relation to the pole piece of the coil magnet, a diaphragm actuating member carried by the armature, the cooperating faces of the pole piece of the coil magnet and of the armature being reversely inclined in .a direction toward the pivotal center of the armature, and means for moving the coil magnet andv armature relatively to each other in a direction parallel to the inclination of said cooperating faces.

3. ln-a sound reproducing apparatus, a diaphragm, a permanent magnet, a coil magnet operatively associated with the permanent magnet, an armature adapted to be actuated by the coil magnet, said armature being pivoted adjacent the diaphragm and operatively associated therewith, and means for moving the coil magnet toward and away from the pivotal center of the arma= ture tovary the leverage of the armature and to vary the air gap between said cooperating faces simultaneously.

4. In a sound reproducing apparatus, a diaphragm, a permanent magnet, a coil magnet carried by the permanent magnet, an armature pivotally mounted in operative relation to the pole piece of the coil magnet, a diaphragm actuating member carried by the armature, the cooperating faces of the pole piece of the coillnagnet and of the armature being reverselv inclined in a directionv toward the pivotal center of the armature, and means for moving the permanent magnet longitudinally of the arma ture, thereby adjusting the coil magnet toward or away from the pivotal center of the armature and moving the (moperatina moms? faces of the armature and pole piece in the direction of their inclination.

' 5. In a sound reproducing apparatus, a diaphragm, a permanent magnet, a coil magnet operatively associated with the permanent magnet, a pivoted armature adapted to be actuated by the coil magnet and operatively associated with the diaphragm,

magnet associated with the permanent magnet, an armature pivotally mounted in 0perative relation to the pole piece of the coil magnet, a diaphragm actuating member carried by the armature, the cooperating parts of the armature and the pole piece of the magnet having a portion of their opposed faces parallel to each otherand another portion of their opposed faces reversely i11- clined in a direction toward the pivotal center of the armature. 1

7.111 a sound reproducing apparatus, a

diaphragm, a permanent magnet, a coil operativelyassociated With the permanent magnet, and a pivoted armature adapted to be actuated by the coil magnet, said armature being operatively associated With the diaphragm, the leverage, of said pivoted armature and the air space between the coil magnet and said armature being simultaneously variable by moving the coil magnet in onedirection only.

8. In a sound reproducing apparatus, a

dia'phragm, a permanent magnet, a coil magnet, an armature operatively connected to said diaphragm, said armature being pivoted and adapted to be actuated by the coil magnet, and the magnet of said armature and the airgap between said armature and coil magnet being variable by a movement of one of said elements in one direction only.

LEO L. HUGHES. 

